Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1751741AbWCUOrN (ORCPT ); Tue, 21 Mar 2006 09:47:13 -0500 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1751740AbWCUOrN (ORCPT ); Tue, 21 Mar 2006 09:47:13 -0500 Received: from pentafluge.infradead.org ([213.146.154.40]:37058 "EHLO pentafluge.infradead.org") by vger.kernel.org with ESMTP id S1751741AbWCUOrM (ORCPT ); Tue, 21 Mar 2006 09:47:12 -0500 Subject: Re: referring a user address from ioctl entry point From: Arjan van de Ven To: yogeshwar sonawane Cc: linux-kernel In-Reply-To: References: Content-Type: text/plain Date: Tue, 21 Mar 2006 15:47:08 +0100 Message-Id: <1142952429.3077.87.camel@laptopd505.fenrus.org> Mime-Version: 1.0 X-Mailer: Evolution 2.2.3 (2.2.3-2.fc4) Content-Transfer-Encoding: 7bit X-SRS-Rewrite: SMTP reverse-path rewritten from by pentafluge.infradead.org See http://www.infradead.org/rpr.html Sender: linux-kernel-owner@vger.kernel.org X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 637 Lines: 17 On Tue, 2006-03-21 at 20:14 +0530, yogeshwar sonawane wrote: > Hi all, > > can we write directly to user virtual address from kernel space? > i.e. dereferencing a user address from driver entry point? > No this is not allowed and a big security hole at minimum. You HAVE to use copy_from_user / copy_to_user and similar API to do this. Be glad the FC3 kernel doesn't allow this at all ;) - To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/